GB2412684A

GB2412684A - Sand control screen assembly and treatment methods

Info

Publication number: GB2412684A
Application number: GB0512579A
Authority: GB
Inventors: Jr Travis T Hailey; Thomas O Roane; Ralph H Echols
Original assignee: Halliburton Energy Services Inc
Current assignee: Halliburton Energy Services Inc
Priority date: 2002-01-25
Filing date: 2003-01-22
Publication date: 2005-10-05
Anticipated expiration: 2023-01-22
Also published as: GB0512579D0; US20030141060A1; WO2003064811A3; GB2403239A; GB0417114D0; AU2003207624A1; GB2412684B; WO2003064811A2; US6719051B2; GB2403239B

Abstract

A sand control screen assembly (40) and method for treating formations traversed by a wellbore (34) in a single trip are disclosed. The sand control screen assembly (40) includes a base pipe (56) with a plurality of opening (58) that allow fluid flow therethrough. A filter medium (62) is positioned about the exterior of the base pipe (56) to filter particulate matter out of the production fluids. One-way valves (70) are operably associated within the openings (58) of the base pipe (56) to prevent fluid flow from the interior of the base pipe (56) to the exterior of the base pipe (56) during a treatment process. The one-way valves (70), however, are actuable to allow fluid flow from the exterior of the base pipe (56) to the interior of the base pipe (56) to allow production of fluids from the formation (14). Methods for fracturing, frac packing and gravel packing treatments are disclosed.

Description

24 1 2684

SAND CONTROL SCREEN ASSEMBLY AND TREATMENT METHOD

USING THE SAME

This invention relates, in general, to a sand control screen assembly positioned in a production interval of a wellbore and, in particular, to a sand control screen assembly having a seal member that prevents fluid flow from the interior to the exterior of the sand control screen assembly during the treatment of single or multiple formations during a single trip into the well.

It is well known in the subterranean well drilling and completion art that relatively fine particulate materials may be produced during the production of hydrocarbons from a well that traverses an unconsolidated or loosely consolidated formation. Numerous problems may occur as a result of the production of such particulate. For example, the particulate causes abrasive wear to components within the well, such as tubing, pumps and valves. In addition, the particulate may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids using surface processing equipment.

One method for preventing the production of such particulate material is to gravel pack the well adjacent to the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a sand control screen is lowered into the wellbore on a work string to a position proximate the desired production interval. A fluid slurry including a liquid carrier and a relatively coarse particulate material, such as sand, gravel or proppants which are typically sized and graded and which are typically referred to herein as gravel, is then pumped down the work string and into the well annulus formed between the sand control screen and the perforated well casing or open hole production zone.

The liquid carrier either flows into the formation or returns to the surface by flowing through a wash pipe or both. In either case, the gravel is deposited around the sand control screen to form the gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the fine particulate materials carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of these particulate materials from the formation.

It has been found, however, that following a gravel packing operation, the fluid inside the sand control screen tends to leak off into the adjacent formation. This leak off not only results in the loss of the relatively expensive fluid into the formation, but may also result in damage to the gravel pack around the sand control screen and the formation by, for example, fracturing a formation when it is not desirable to fracture that formation. This fluid leak off is particularly problematic in cases where multiple production intervals within a single wellbore require gravel packing as the fluid remains in communication with the various formations for an extended period of time.

In other cases, it may be desirable to perform a formation fracturing and propping operation prior to or simultaneously with the gravel packing operation. Hydraulic fracturing of a hydrocarbon formation is sometimes necessary to increase the permeability of the formation adjacent the wellbore. According to conventional practice, a fracture fluid such as water, oil, oil/water emulsion, gelled water or gelled oil is pumped down the word string with sufficient volume and pressure to open multiple fractures in the production interval. The fracture fluid may carry a suitable propping agent, such as sand, gravel or proppants, which are typically referred to herein as proppants, into the fractures for the purpose of holding the fractures open following the fracturing operation.

The fracture fluid must be forced into the formation at a flow rate great enough to fracture the formation allowing the entrained proppant to enter the fractures and prop the formation structures apart, producing channels which will create highly conductive paths reaching out into the production interval, and thereby increasing the reservoir permeability in the fracture region. As such, the success of the fracture operation is dependent upon the ability to inject large volumes of hydraulic fracture fluid along the entire length of the formation at a high pressure and at a high flow rate.

It has been found, however, that it is difficult to fracture multiple formations traversed by the wellbore that are within a relatively close proximity of one another. This difficulty is the result of the complexity and length of the permanent downhole tools and the associated service tools used to perform the fracture operation. Accordingly, if formations are closer together than the axial length required for the permanent downhole tools and service tool, then certain of the formations cannot be isolated for individual treatment processes.

Therefore, a need has arisen for an apparatus and a treatment method that provides for the treatment of multiple formations that are located relatively close to one another by allowing the use of relatively simple and compact permanent downhole tools and service tools. A need has also arisen for an apparatus and a treatment method that allow for the gravel packing of one or more production intervals while preventing fluid loss into adjacent formations.

The present invention provides a single trip method as recited in the appended independent claim 1. Further features of the invention are provided as recited in any of the appended dependent claims.

Described hereinafter is a sand control screen assembly positionable within a production interval comprising: a base pipe having at least one opening that allows fluid flow therethrough; a filter medium positioned about the exterior of the base pipe, the filter medium selectively allowing fluid flow therethrough and preventing particulate flow therethrough; and a one-way valve operably associated with the base pipe that controls fluid flow through the opening of the base pipe.

The valve may be one of a plurality of one-way valves. The one-way valve may prevent fluid flow from the interior of the base pipe to the exterior of the filter medium and may be actuatable to allow fluid flow from the exterior of the filter medium to the interior of the base pipe. The base pipe ideally includes a plurality of openings and the one-way valve may further comprise a plurality of one-way valves each disposed at least partially within one of the openings of the base pipe, the one-way valves preventing fluid flow from the interior of the base pipe to the exterior of the filter medium and being actuatable to allow fluid flow from the exterior of the filter medium to the interior of the base pipe. These oneway valves may be flush mounted within the openings of the base pipe. Alternatively, these one-way valves may extend partially inwardly into the base pipe. The one-way valves ideally reduce the inner diameter of the base pipe by no more than about thirty percent. The one-way valves may reduce the inner diameter of the base pipe by between about ten percent and about thirty percent. The one-way valves may extend partially outwardly from the base pipe. The one-way valves may increase the outer diameter of the base pipe by no more than about thirty percent. The oneway valves may increase the outer diameter of the base pipe by between about ten percent and about thirty percent. The one-way valves may be ball and seat type one-way valves.

The one-way valve are ideally selectively operable to a disabled configuration such that fluid flow from the interior of the base pipe to the exterior of the filter medium is enabled. The one-way valve further comprise a sliding sleeve and a spring. The one-way valve may further comprise at least one piston and at least one spring.

The base pipe may have a plurality of openings that allow fluid flow therethrough; and said valve may be operably associated with the openings of the base pipe, may prevent fluid flow from the interior of the base pipe to the exterior of the base pipe, and may be actuatable to allow fluid flow from the exterior of the base pipe to the interior of the base pipe.

Preferably, the base pipe has a plurality of openings that allow fluid flow therethrough; and said valve is one of a plurality of one-way valves positioned at least partially within the openings of the base pipe, the one-way valves having a first operating mode wherein the one-way valves prevent fluid flow from the interior of the base pipe to the exterior of the base pipe and are actuatable to allow fluid flow from the exterior of the base pipe to the interior of the base pipe and a second operating mode wherein the one-way valves allow fluid flow from the interior of the base pipe to the exterior of the base pipe and from the exterior of the base pipe to the interior of the base pipe.

Again, these one-way valves may be flush mounted within the openings of the base pipe. Alternatively, the one-way valves may extend partially inwardly into the base pipe.

The one-way valves may reduce the inner diameter of the base pipe by no more than about thirty percent. The one-way valves may reduce the inner diameter of the base pipe by between about ten percent and about thirty percent. The one-way valves extend partially outwardly from the base pipe. The one-way valves may increase the outer diameter of the base pipe by no more than about thirty percent. The one-way valves may increase the outer diameter of the base pipe by between about ten percent and about thirty percent. The one- way valves may be ball and seat type one-way valves. The one-way valves may be operated from the first operating mode to the second operating mode in response to a preselected differential pressure.

Ideally, the valve is positioned in a fluid flow path between the filter medium and the at least one opening in the base pipe, prevents fluid flow from an interior of the base pipe to an exterior of the filter medium, and is actuatable to allow fluid flow from the exterior of the filter medium to the interior of the base pipe. The one-way valve may further comprise a sliding sleeve and a spring. The one-way valve may further comprise at least one piston and at least one spring. The one-way valve may be selectively operable to a disabled configuration such that fluid flow from the interior of the base pipe to the exterior of the filter medium is enabled. The one-way valve is positioned to the exterior of the base pipe.

The at least one opening may be one of a plurality of openings allowing fluid flow through the base pipe; and the valve may comprise a sleeve disposed within the base pipe that controls fluid flow through the openings of the base pipe. The sleeve may further comprise a plurality of ports, the sleeve having a first position and a second position relative to the base pipe, wherein, the first position, the ports of the sleeve are not aligned with the openings of the base pipe, and in the second position, the ports of the sleeve are aligned with the openings of the base pipe. The sleeve may be axially displaceable between the first position and the second position. The sleeve may be rotatably displaceable between the first position and the second position. The sleeve may also be removable.

Also, preferably the base pipe is a tubular member, the or each opening is a fluid passageway in a sidewall section of the tubular member; the filter medium is positioned exteriorly around the tubular member defining a first annular region with the tubular 1 1 member; a housing is positioned exteriorly around the tubular member defining a second annular region with the tubular member; and the valve comprises a sleeve slidably positioned within the second annular region, the sleeve having a sealing position and a nonsealing position, the sleeve being mechanically biased toward the sealing position, the sleeve being operated to the sealing position when a force generated by differential pressure acting on the sleeve between an exterior of the filter medium and an interior of the base pipe does not exceed the mechanical bias force, thereby preventing fluid flow from the interior of the base pipe to the exterior of the filter medium, the sleeve being operated to the nonsealing position when the force generated by differential pressure acting on the sleeve between the exterior of the filter medium and the interior of the base pipe exceeds the mechanical bias force, thereby allowing fluid flow from the exterior of the filter medium to the interior of the base pipe.

The sleeve may further comprise an annular sleeve. Alternatively, the sleeve may further comprise a non-annular sleeve. The mechanical bias force may be generated by a sprmg.

A downhole treatment method is also described below, the method comprising the steps of: locating a sand control screen assembly within a production interval of a wellbore, the sand control screen assembly including a base pipe having at least one opening and a filter medium positioned about an exterior of the base pipe; pumping a treatment fluid into the production interval; and preventing fluid flow from an interior to an exterior of the sand control screen assembly with at least one one- way valve operably associated with the base pipe that controls fluid flow through the at least one opening of the base pipe.

The at least one valve is ideally one of a plurality of one-way valves. The at least one opening ideally further comprises a plurality of openings and the at least one one-way valve further comprises a plurality of one-way valves and wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assembly further comprises positioning one of the one-way valves at least partially within each of the openings of the base pipe.

The step of positioning one of the one-way valves at least partially within each of the openings of the base pipe may further comprise flush mounting the one-way valves within the openings of the base pipe. The step of positioning one of the one-way valves at least partially within each of the openings of the base pipe may further comprise extending the one-way valves partially inwardly into the base pipe. The step of positioning one of the one- way valves at least partially within each of the openings of the base pipe may further comprise extending the one-way valves partially outwardly from the base pipe.

Preferably, the method further comprises selectively operating the oneway valves to a disabled configuration allowing fluid flow from the interior of the sand control screen assembly to the exterior of the sand control screen assembly. The method may further comprise the step of allowing fluid flow from the exterior of the sand control screen assembly to the interior of the sand control screen assembly through the at least one one-way valve. The method may comprise the step of continuing to prevent fluid flow from the interior to the exterior of the sand control screen assembly after terminating the pumping of the treatment fluid into the production interval. The step of preventing fluid flow from the interior to the exterior of the sand control screen assembly may further comprise positioning the at least one one-way valve in a fluid path between the f Iter medium and the opening of the base pipe. The step of positioning the at least one one-way valve in a fluid path between the filter medium and the opening of the base pipe may further comprise positioning a sliding sleeve in the fluid path between the filter medium and the opening of the base pipe. The step of positioning the at least one one-way valve in a fluid path between the filter medium and the opening of the base pipe may further comprise positioning at least one piston in the fluid path between the filter medium and the opening of the base pipe.

The method may further comprise selectively operating the at least one one-way valve to a disabled configuration allowing fluid flow from the interior of the sand control screen assembly to the exterior of the sand control screen assembly.

Ideally, the fluid flow from the interior to the exterior of the sand control screen assembly is prevented by positioning at least one one-way valve in a fluid path between the exterior and the interior of the sand control screen; and further comprising the steps of allowing fluid flow from the exterior to the interior of the sand control screen assembly through the one-way valve; and selectively operating the one-way valve to a disabled configuration allowing fluid flow from the interior of the sand control screen assembly to the exterior of the sand control screen assembly.

The step of positioning at least one one-way valve in a fluid path between the exterior and the interior of the sand control screen may further comprise positioning the one-way valve to the exterior of the base pipe. The step of selectively operating the one-way valve to a disabled configuration may further comprise exposing the one-way valve to a differential pressure above a preselected level. The step of positioning at least one one-way valve in a fluid path between the exterior and the interior of the sand control screen may further comprise positioning the one-way valve at least partially within the opening of the base pipe.

The step of positioning at least one one-way valve in a fluid path between the exterior and the interior of the sand control screen may further comprise extending the one-way valve partially inwardly into the base pipe. The step of positioning at least one one-way valve in a fluid path between the exterior and the interior of the sand control screen may further comprise extending the one-way valve partially outwardly from the base pipe.

Also, the base pipe may comprise a plurality of openings and the at least one valve may control fluid flow through the openings. The method may further comprise the step of allowing fluid flow from the exterior of the base pipe to the interior of the base pipe through the at least one valve. The step of pumping a treatment fluid into the production interval may further comprise pumping a fracture fluid into the production interval and fracturing a formation. The step of pumping a treatment fluid into the production interval may further comprise pumping a gravel packing fluid into the production interval and gravel packing the production interval. The method may further comprise the step of continuing to prevent fluid flow from the interior to the exterior of the sand control screen assembly after terminating the pumping of the treatment fluid.

In the downhole treatment method, the at least one valve may comprise a seal member, and may comprise the further step of filling the interior of the sand control screen assembly with a sand plug.

The treatment fluid may be a fracture fluid, and the method may comprise the further step of fracturing formation traversed by the wellbore. A gravel packing fluid may be pumped into the production interval and the production interval is gravel packed.

Preferably, the step of filling the interior of the sand control screen assembly with a sand plug further comprises pumping a first treatment fluid containing first solid agents into the interior of the sand control screen assembly and wherein a second treatment fluid is pumped into a formation traversed by the wellbore, a third treatment fluid containing second solid agents is pumped into the production interval, and the pumping of the third treatment fluid is terminated when the production interval is packed with the second solid agents. The step of preventing fluid flow from the interior to the exterior of the sand control screen assembly may further comprise preventing fluid flow from the interior to the exterior of the sand control screen assembly with a sleeve operably associated with the base pipe of the sand control screen assembly that controls fluid flow through the openings of the base pipe. The step of preventing fluid flow from the interior to the exterior of the sand control screen assembly may further comprise preventing fluid flow from the interior to the exterior of the sand control screen assembly with removable plugs positioned within the openings of the base pipe. The at least one valve may comprise a sleeve disposed within the base pipe that controls fluid flow through the openings of the base pipe. The method may further comprise the step of allowing fluid flow through the base pipe by axially shifting the sleeve from a first position to a second position to align ports in the sleeve with the openings of the base pipe. The method may further comprise the step of allowing fluid flow through the base pipe by rotatably shifting the sleeve from a first position to a second position to align ports in the sleeve with the openings of the base pipe. The method may yet further comprise the step of allowing fluid flow through the base pipe by removing the sleeve.

The step of pumping a treatment fluid into the production interval may further comprise pumping a fracture fluid into the production interval and fracturing a formation.

The step of pumping a treatment fluid into the production interval may further comprise pumping a gravel packing fluid into the production interval and gravel packing the production interval. The method may further comprise the step of continuing to prevent fluid flow from the interior to the exterior of the sand control screen assembly after terminating the pumping of the treatment fluid.

The downhole treatment method may comprise the steps of: locating the sand control screen assembly within the wellbore proximate formation to be fractured; the base pipe of the sand control screen assembly having a plurality of openings; pumping a fracture fluid into the formation; and fracturing the formation. The method may further comprise the step of continuing to prevent fluid flow from the interior to the exterior of the sand control screen after terminating the pumping of the fracture fluid.

Also, a method is described hereinafter for treating a formation traversed by a wellbore, the method comprising the steps of: positioning a sand control screen assembly into a work string and locating the sand control screen assembly within a production interval of the wellbore proximate the formation; pumping a first treatment fluid containing first solid agents through the work string into the interior of the sand control screen assembly; pumping a second treatment fluid through the work string into the formation; pumping a third treatment fluid containing second solid agents into the production interval; and terminating the pumping of the third treatment fluid.

The step of pumping a second treatment fluid further may comprise pumping a second treatment fluid comprising third solid agents. The concentration of third solid agents in the second treatment fluid may be lower than the concentration of first solid agents in the first treatment fluid. The concentration of third solid agents in the second treatment fluid may be lower than the concentration of second solid agents in the third treatment fluid.

The method may further comprise the step of preventing fluid flow from the interior to the exterior of the sand control screen assembly with at least one valve operably associated with a base pipe of the sand control screen assembly that controls fluid flow through openings of the base pipe. Also, the method may further comprise the step of preventing fluid flow from the interior to the exterior of the sand control screen assembly with a seal member operably associated with a base pipe of the sand control screen assembly that controls fluid flow through openings of the base pipe. The viscosity of the second treatment fluid may be higher than the viscosity of the first treatment fluid. The viscosity of the second treatment fluid may be higher than the viscosity of the third treatment fluid.

A sand control screen assembly and method for treating multiple formations traversed by a wellbore in a single trip is described hereinafter. The sand control screen assembly of the present invention provides for the treatment of relatively closely spaced formations by allowing the use of relatively simple and compact permanent downhole tools and service tools. In addition, the sand control screen assembly of the present invention prevents undesirable fluid loss from the interior thereof to an adjacent formation.

The sand control screen assembly described herein includes a base pipe with multiple openings designed to allow fluid flow therethrough. A filter medium is positioned about the exterior of the base pipe to filter particulate matter during hydrocarbon production. A seal member is operably associated with the openings of the base pipe to selectively prevent fluid flow through the sand control screen assembly. The seal member may include plugs, a sleeve, one-way valves or the like to achieve this result.

If one-way valves serve as the seal member, the one-way valves may be positioned at least partially within the openings of the base pipe to prevent fluid flow from the interior of the base pipe to the exterior of the base pipe. The one-way valves are actuatable to allow fluid flow from the exterior of the base pipe to the interior of the base pipe to, for example, allow fluid returns to flow therethrough during a gravel packing operation or to allow production fluids to flow therethrough. In addition, after the initial treatment process is completed, some embodiments of the one-way valves may be selectively operated to a disabled configuration such that fluid flow from the interior of the base pipe to the exterior of the base pipe is enabled.

In one embodiment of the sand control screen assembly of the present invention, the one-way valves are flush mounted within the openings of the base pipe. In another embodiment, the one-way valves may extend partially inwardly into the base pipe. In yet another embodiment, the one- way valves may extend partially outwardly from the base pipe.

In still another embodiment, the one-way valves may extend partially outwardly from the base pipe and partially inwardly into the base pipe.

A downhole treatment method is also described which comprises locating the sand control screen assembly within a production interval of a wellbore, preventing fluid flow from the interior to the exterior of the sand control screen assembly with a plurality of one- way valves operably associated with the base pipe that control fluid flow through the openings of the base pipe and pumping a treatment fluid into the production interval. The treatment method may also comprise allowing fluid flow from the exterior to the interior of the sand control screen assembly through the one-way valves and exposing the one-way valves to a differential pressure above a preselected level to selectively operate the one-way valves to a disabled configuration that allows fluid flow from the interior of the sand control screen assembly to the exterior of the sand control screen assembly.

For a more complete understanding of the features and advantages of the present invention, reference is now made to a detailed description of embodiments of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: Figure l is a schematic illustration of an offshore oil and gas platform operating a pair of sand control screen assemblies of the present invention; Figure 2 is a partial cut away view of a sand control screen assembly of the present invention having a seal member disposed within a base pipe; Figure 3A-3D are cross sectional views of a sand control screen assembly of the present invention having a seal member comprising a plurality of one-way valves; Figure 4 is a cross sectional view of an alternate embodiment of the sand control screen assembly of the present invention wherein the seal member comprises a plurality of plugs; Figures 5, 6A-6B and 7A-7B are cross sectional views of alternate embodiments of a sand control screen assembly of the present inventionwherein the seal member comprises a sliding sleeve; Figure 6 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention before a downhole treatment process; Figure 7 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a first phase of a downhole treatment process; Figure 8 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a second phase of a downhole treatment process; Figure 9 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a third phase of a downhole treatment process; Figure 10 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a fourth phase of a downhole treatment process; Figure l l is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a fifth phase of a downhole treatment process; Figure 12 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a sixth phase of a downhole treatment process; Figure 13 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a seventh phase of a downhole treatment process; Figure 14 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during an eighth phase of a downhole treatment process; Figure 15 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention before a downhole treatment process; Figure 16 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a first phase of a downhole treatment process; Figure 17 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a second phase of a downhole treatment process; and Figure 18 is a half sectional view of a downhole production environment including a pair of sand control screen assemblies of the present invention during a third phase of a downhole treatment process.

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts.

The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.

Referring initially to figure 1, a pair of sand control screen assemblies used during the treatment of multiple intervals of a wellbore in a single trip and operating from an offshore oil and gas platform is schematically illustrated and generally designated 10. A semi- submersible platform 12 is centered over a pair of submerged oil and gas formations 14, 16 located bellow a sea floor 18. A subsea conduit 20 extends from a deck 22 of the platform 12 to a wellhead installation 24 including blowout preventers 26. Platform 12 has a hoisting apparatus 28 and a derrick 30 for raising and lowering pipe strings such as a work string 32.

A wellbore 34 extends trough the various earth strata including formations 14, 16. A casing 36 is cemented within wellbore 34 by cement 38. Work string 32 includes various tools such as a sand control screen 40 which is positioned within production interval 44 between packers 46, 48 and adjacent to formation 14 and sand control screen 42 which is positioned within production interval 50 between packers 52, 54 and adjacent to formation 16. Thereafter, a treatment fluid containing sand, gravel, proppants or the like is pumped down work string 32 such that formations 14, 16 may be sequentially treated.

Even though figure 1 depicts a vertical well, it should be noted by one skilled in the art that the sand control screen assemblies of the present invention are equally well-suited for use in wells having other directional orientations such as deviated wells, inclined wells or horizontal wells. Also, even though figure 1 depicts an offshore operation, it should be noted by one skilled in the art that the sand control screen assemblies of the present invention are equally wellsuited for use in onshore operations. Also, even though figure 1 depicts two formations, it should be understood by one skilled in the art that the treatment processes of the present invention are equally well-suited for use with any number of formations.

Referring now to figure 2 therein is depicted a more detailed illustration of a sand control screen assembly of the present invention, such as, for example, sand control screen assembly 40 of figure 1. Sand control screen assembly 40 includes a base pipe 56 that has a plurality of openings 58 which allow the flow of production fluids into sand control screen assembly 40.

The exact number, size and shape of openings 58 are not critical to the present invention, so long as sufficient area is provided for fluid production and the integrity of base pipe 56 is maintained.

Spaced around base pipe 56 is apluralityofribs 60. Ribs 60 are generally symmetrically s distributed about the axis of base pipe 56. Ribs 60 are depicted as having a cylindrical cross section, however, it should be understood by one skilled in the art that ribs 60 may alternatively have a recta ngular or triangular cross section or other suitable geometry. Additionally, it should be understood by one skilled in the art that the exact number of ribs 60 will be dependent upon Me diameter of base pipe 56 as well as other design characteristics that are well known in the lo art.

Wrapped around ribs 60 is a screen wire 62. Screen wire 62 forms a plurality of turns, such as turn 64 and turn 66. Between each ofthe tutus is a gap through which formation fluids flow. The number of tarns and the gap between the turns are determined based upon the characteristics of the formation from which fluid is being produced and the size of the gravel Is to be used dunug the gravel packing operation. Together, ribs 60 and screen wire 62 may form a sand control screen jacket which is attached to base pipe 56 by welding or other suitable techniques.

A one-way valve 70 is disposed within each opening 58 of base pipe 56 to prevent fluid flow from the interior to the exterior ofthe sand control screen assembly40. One-way valves so 70 may be referred to collectively as a seal member 68. Preferably, one-way valves 70 are mounted within openings 58 by threading, stamping or other suitable technique. Ball and seat type one-way valves have been found to be suitable, however, other types of one-way valves may also be used including poppet valves, sleeve valves and the like. One-way valves 70 prevent fluid flow from the interior to the exterior of sand control screen assembly 40 and are as actuatable to allow fluid flow from the exterior to the interior of sand control screen assembly 40. Accordingly, when one-way valves 70 are used within base pipe 56 of sand control screen assembly 40 during production, production fluids are allowed to flow through sand control screen assembly 40 through one-way valves 70.

Refernug now to figure 3A, therein is depicted a sand control screen assembly that is so generally designated 40A. Sand control screen assembly 40A is substantially identical to sand control screen assembly 40 described above as sand control screen assembly 40A includes base pipe 56 that has a plurality of openings 58, a plurality of ribs (not pictured) and a screen wire 62. Together, the ribs and screen wire 62 fonn a sand control screenjacket that is attached using connectors 69 to base pipe 56 by welding or other suitable techniques.

One-way valves 70A are disposed within each opening 58 of base pipe 56 to prevent fluid flow from the interior to the exterior of the sand control screen assembly 40A. One-way valves 70A may be referred to collectively as a seal member 68. Preferably, one-way valves 70A are flush mounted within openings 58 by threading, stamping or other suitable technique.

One-way valves 70A prevent fluid flow from the interior to the exterior of sand control screen assembly 40A and are actuatable to allow fluid flow from the exterior to the interior of sand control screen assembly 40A. Accordingly, when one-way valves 70A are used within base pipe lo 56 of send control screen assembly40Aduringproduction,production fluids are allowed to flow through sand control screen assembly 40A through one-way valves 70A.

Following the downhole treatment processes discussed in detail below wherein fluid flow from the interior to the exterior of sand control screen assembly 40A is prevented, the ability to flow fluids from the interior to the exterior of sand control screen assembly 40A may be desirable, for example, to perfonn an acid treatment. Accordingly, oneway valves 70A may be designed to lock out or be rendered inoperable under certain conditions such that one-way valves 70A no longer prevent fluid flow from the interior to the exterior of sand control screen assembly 40A. In such cases, after one-way valves 70A have been operated into the lock out position, fluid flow is allowed from the exterior to the interior and from the interior to the to exterior of sand control screen assembly 40A. One method of locking out one-way valves 70A is to expose one-way valves 70A to a differential pressure above a predetermined threshold.

Referring now to figure 3B, therein is depicted a sand control screen assembly that is generally designated 40B. Sand control screen assembly 40B is substantially similar to sand control screen assembly40A described above as sand control screen assembly40B includes base as pipe 56 that has a plurality of openings 58, a plurality of ribs (not pictured) and a screen wire 62. Together, the ribs and screen wire 62 fonn a sand control screen j acket that is attached using connectors 69 to base pipe 56 by welding or other suitable techniques.

One-way valves 70B are disposed within each opening 58 of base pipe 56 to prevent fluid flow from the interior to the exterior of the sand control screen assembly 40B. One-way so valves 70Bmaybereferredto collectively es asealmember68. Preferably, one-wayvalves70B are mounted within openings 58 by threading, stamping or other suitable technique. In the illustrated embodiment, one-way valves 70B extend from openings 58 into base pipe 56. Due to the thickness of the wall of base pipe 56, it may be desirable to use one-way valves 70B that are thicker than the wall of tease pipe 56. In this case, it has been found that ore-way valves 70B may extend into base pipe 56 and may reduce the inner diameter of base pipe 56 up to thirty percent without having a detrimental impact on the installation or operation of sand control screen assembly 40B during treatment or production. Preferably, one-way valves 70B may s reduce the inner diameter of base pipe 56 between about ten and thirty percent.

As an alternative and as depicted in figure 3C, one-way valves 70C may be disposed within each opening 58 of base pipe 56 to prevent fluid flow from the interior to the exterior of the sand control screen assembly 40C. One-way valves 70C maybe referred to collectively as a seal member 68. Preferably, one-way valves 70C are mounted within openings 58 by to threading, stamping or other suitable technique. Intheillustrated embodiment, ore-way valves 70C extend from openings 58 outwardly from base pipe 56 toward screen wire 62. In his embodiment, the ribs (not pictured) must be positioned around base pipe 56 such that openings 58 may receive one-way valves 70C that are thicker than the wall of base pipe 56. In this configuration, base pipe 56 retains its hill bore capabilities. Preferably, one-way valves 70C may increase the outer diameter of base pipe 56 between about ten and thirty percent.

As yet an alternative and as depicted in figure 3D, ore-way valves 70D maybe disposed within each opening 58 of base pipe 56 to prevent fluid flow from the interior to the exterior of the sand control screen assembly 40D. One-way valves 70D maybe referred to collectively as a seal member 68. Preferably, one-way valves 70D are mounted within openings 58 by threading, sniping or other suitable technique. Intheillustrated embodiment, ore-way valves 70D extend inwardly and outwardly from openings 58 of base pipe 56. In his embodiment, the ribs (not pictured) must be positioned around base pipe 56 such that openings 58 may receive ore-way valves 70D that are thicker then the wall of tease pipe 56. Preferably, ore-way valves 70D may increase the outer diameter of base pipe 56 between about ten and thirty percept and may reduce the inner diameter of base pipe 56 between about ten and thirtypercent.

Referring now to figure 4, therein is depicted an alternative embodiment of a sand control screen assembly that is generally designated 71. Sand control screen assembly 71 includes base pipe 56 having a plurality of openings 58 with screen wire 62 wrapped therearound and attached to base pipe 56 with connectors 69. Disposed within openings 58 of so base pipe 56 are a plurality of plugs 72 that prevent fluid flow through openings 58 and serve as seal member 68 in this embodiment. Following the dowrhole treatment processes discussed in more detail below, plugs 72 are removed from openings 58 such that production fluids may flow to the interior of sand control screen assembly 71.

Plugs 72 may be any conventional plugs known or unknown in the art, including metal plugs, such as aluminum plugs, ceramic plugs or the like. The techniques used to remove plugs 72 will depend upon the construction of plugs 72. If plugs 72 are formed from an acid reactive material such as aluminum, an acid treatment may be used to remove plugs 72. The acid may s be pumped into the interior of sand conko1 screen assembly 71 where it will react with the reactive plugs, thereby chemically removing plugs 72.

Alternatively, regardless of the type of plug, plugs 72 may be mechanically removed.

For example, a scraping mechanism may be used to physically contact plugs 72 and remove plugs 72 from the openings 58. As another alternative, if plugs 72 are constructed from lo propellants, a combustion process maybe used to remove plugs 72. Likewise, if plugs 72 are constructedfromfriablematerials such as ceramics, avibrationprocess, such as sonic vibrations may be used to remove plugs 72. As a further alternative, plugs 72 maybe removed by applying a preselected amount of differential pressure across plugs 72.

Refernug now to figure 5, an alternative embodiment of a sand control screen assembly Is is illustrated and generally designated 73. Sand control screen assembly 73 includes base pipe 56 havingapluralityofopenrugs 58 with screen wire 62 wrapped therearound. Disposedwithin base pipe 56 is a sleeve 74 having multiple ports 76 that serves as seal member 68 in this embodiment. When in a first position, ports 76 of sleeve 74 do not align with openings 58 of the base pipe 56. When in a second position, ports 76 of sleeve 74 align with. openings 58 of to base pipe 56. When sleeve 74 is in the first position, fluid flow from the exterior of sand control screen assembly 73 to the interior of sand control screen assembly 73 is prevented, as is fluid flow from the interior to the exterior of sand control screen assembly 73. When sleeve 74 is in the second position, fluid flow from the exterior of sand control screen assembly 73 to the interior of the sand control screen assembly 73 is allowed, as is fluid flow from the interior to Is the exterior of sand control screen assembly 73. Sleeve 74 can be displaced between the first position and secondpositionbyanyconventionalmeans such as axialdisplacementorrotational displacement. In an alternative embodiment, sleeve 74 can be a removable sleeve in which case ports 76 are not required.

Referring now to figure 6A-6B, therein is depicted another embodiment of a sand control so screen assembly of the present invention that is generally designated 132. Sand control screen assembly 132 includes abase pipe 134 Mat has a non perforated section and aperforated section that includes a series of operungs 136 that are circumferentially spaced therearound. Sand control screen assembly 132 has a pair of screen connectors 138, 140 that attach a sand control screen 142 to base pipe 134. Screen connectors 138, 140 may be attached to base pipe 134 by welding or other suitable technique. Sand control screen 142 may comprise a screen wire wrapped around a plurality of ribs as described above. Sand control screen 142 is disposed around the section of base pipe 134 that is not perforated.

s Screen connectors 138,140 attach sand control screen 142 to base pipe 134 such that an annulus 144 is formed between sand control screen 142 and base pipe 134. It should be noted that centralizers or other support members maybe disposed within annulus 144 to support sand control screen 142 and maintain the standoff between sand control screen 142 and base pipe 134. Screen connector 140 includes one or more fluid passageways 146. Screen connector 140 lo also has an upper sealing surface 148. Coupled to the upper end of screen connector 140 is a housing member 150. Housing member 150 forms an armulus 152 with base pipe 134 adjacent to openings 136. Disposed within annulus 152 is an annular sliding sleeve 154 having a sealing surface 156 which is preferably made from a resilient material such as an elastomer or polymer.

Also disposed within annulus 152 is a spiral wound compression spring 158 that downwardly Is biases sliding sleevelS4.

Together, spring 158, sliding sleeve 154andscreenconnector 140foanannularone wayvalve 160 that maybe referred to as a seal member. One-way valve 160prevents fluid flow from the interior to the exterior of sand control screen assembly 132, as best seen in figure 6A, and is actuatable to allow fluid flow from the exterior to the interior of sand control screen to assembly 132, as best seen in figure 6B. For example, during a treatment process as described below wherein a treatment fluid is pumped into the interior of sand control screen assembly 132 and is discharged into the wellbore annulus above sand control screen assembly 132, fluid flow from the interior to the exterior of sand control screen assembly 132 is prevented. Specifically, the bias force of spring 158 and the force created by differential pressure across sliding sleeve :5 154 between the interior and the exterior of sand control screen assembly 132 both act downwardly on sliding sleeve 154 such that sealing surface 156 sealingly engages sealing surface 148 of screen connector 140, thereby preventing fluid flow from the interior to the exterior of sand control screen assembly 132.

During production, production fluids are allowed to flow from the exterior to the interior lo of sand control screen assembly 132 through a fluid flow paw within sand control screen assembly 132. Specifically, the fluid flows through sand control screen 142, travels along tease pipe 134 in annulus 144, passes &rough fluid passageways 146 in screen connector 140 to unseat sliding sleeve 154 from sealing surface 148 of screen connector 140 by compressing spring 158, then travels around sliding sleeve 154, which may include a fluid bypass (not pictured), in arnulus 152 and through openings 136.

Following the downhole treatment processes discussed below wherein fluid flow from the interior to the exterior of sand control screen assembly 132 is prevented, the ability to flow s fluids from the interior to the exterior of sand control screen assembly 132 may be desirable, for example, to perform an acid treatment. Accordingly, one-way valve 160 may be designed to lock out or be rendered inoperable under certain conditions such that one-way valve 160 no longer prevents fluid flow from the interior to the exterior of sand control screen assembly 132.

For example, in the illustrated embodiment, when a sufficient differential pressure is placed lo across sliding sleeve 154 between the interior and the exterior of sand control screen assembly 132, a ceramic disk 161 in bypass passageway 159 may rupture to permanently open bypass passageway 159. In such cases, after one-way valve 160 has been rendered inoperable, fluid flow is allowed from the exterior to the interior and from *e interior to the exterior of sand control screen assembly 132.

Is Referring now to figure 7A-7B, therein is depicted another embodiment of a sand control screen assembly of the present invention that is generally designated 162. Sand control screen assembly 162 includes a tease pipe 164 that has anonperforatedsectionandaperforatedsection that includes a series of openings 166 that are circumferentially spaced therearound. Sand control screen assembly 162 has apair of screen connectors 168, 170 that attach a sand control to screen 172 to base pipe 164. Screen connectors 168,170 maybe attached to base pipe 164 by welding or other suitable technique. Sand control screen 172 may comprise a screen wire wrapped around a plurality of ribs as described above. Sand control screen 172 is disposed around the section of base pipe 164 that is not perforated.

Screen connectors 168,170 attach sand control screen 172 to base pipe 164 such that an Is annulus 174 is fanned between sand control screen 172 and base pipe 164. Screen connector includes one or more fluid passageways 176. Coupled to the upper end of screen connector is a housing member 180. Housing member 180 fonns an annulus 182withbasepipe 164 adjacent to openings 166. Disposed withm annulus 182 is an annular sliding sleeve 184. A seal is positioned exteriorly of sliding sleeve 184 to provide a seal against the interior surface so of housing member 180. Likewise, a seal 186 is positioned interiorly of sliding sleeve 184 to provide a seal against the exterior surface of base pipe 164. Preferably seals 185,186 are made from a resilient material such as an elastomer or polymer. Also disposed widen amulus 182 is a spiral wound compression spring 188 that downwardly biases sliding sleeve 184.

Together, spring 188, sliding sleeve 184, housing member 180 and base pipe 164 form an annular one-way valve 190 that may be referred to as a seal member. One-way valve 190 prevents fluid flow from the interior to the exterior of sand control screen assembly 162, as best seen in figure 7A, and is actuatable to allow fluid flow from the exterior to the interior of sand control screen assembly 162, as best seen in figure 7B. Specifically, during a treatment process as described below, a differential pressure force and spring 188 downwardlybias sliding sleeve 184 such that seal 185 is in sealing engagement with the interior surface of housing member 180 and seal 186 is in sealing engagement with the exterior surface of base pipe 164 which prevents fluid flow from the interior to the exterior of sand control screen assembly 162. During to production, production fluids are allowed to flow from the exterior to the interiorofsand control screen assembly 182 by passing through sand control screen 172, traveling along base pipe 164 in annulus 174, passing through fluid passageways 176 in screen connector 170 to shift sliding sleeve 184 such that seal 186 is out of sealing engagement with base pipe 164 by compressing spring 188, then traveling around sliding sleeve 184 in the radially reduced section of base pipe 164 and through openings 166.

Even though figures 6A-7B have been described as including annular sliding sleeves 154, 184, it should be understood by those skilled in the art that the illustrated sliding sleeves 154, 184 could alternatively represent one or more pistons. For example, sliding sleeves 154, 184 could alternatively be one or more serni-nnnular pistons that are acted upon simultaneously to by a single spiral wound compression spring. As a further example, sliding sleeves 154, 184 could alternatively be one or more rod type pistons each of which could be acted upon by a corresponding sprmg.

It should be understood by those skilled in the art that other type of seal members 68 may be used to temporarily prevent fluid flow from the interior to the exterior of a sand control Is screen assembly of the present invention during and following a treatment process of the present invention but allow the flow of production fluids from the exterior to theinteriorthereofwithout departing from the principles of the present invention.

Also, it should be understood by those skilled in the art that while figures 2 - 7B have depicted a wire wrapped sand control screen, other types of filter media could alternatively be so used in conjunction with the apparatus of the present invention, including, but not limited to, a fluid-porous, particulate restricting material such as a plurality of layers of a wire mesh that are diffusion bonded or sintered together to form a porous wire mesh screen designed to allow fluid flow therethrough but prevent the flow of particulate materials of a predetermined size from passing therethrough.

Referring now to figure 8, therein is depicted an embodiment of the present invention that is used during fracturing and frac packing treatments. As illustrated, sand control screen assembly 40 including oneway valves 70, is positioned within casing 36 and is adjacent to formation 14. Likewise, sand control screen assembly 42 including one-way valves 70, is positioned within casing 36 and is adjacent to formation 16. A service tool 78 is positioned within the work string 32. As illustrated by the break between service tool 78 and sand control screen assemblies 40, service tool 78 maybe operablypositioned several feet to several hundred lo feet uphole of sand control screen assembly 40.

To begin the completion process, production interval 44 adjacent to formation 14 is isolated. Packer46 seals the near end of production interval 44 end packer48 seals the far end of production interval 44. Likewise, productioninterval 50 adjacentto Connation 16 is isolated.

Packer 52 seals the near end of production interval 50 and packer 54 seals the far end of is production interval 50. Additionally, seal element 88 is coupled to service tool 78. Seal element 88 contacts the interior of work string 32 forming a seal, thereby preventing fluid flow into the annulus between work stung 32 and service tool 78. Work string 32 includes crossover ports 90, 92 that provide a fluid communication path from the interior of work string 32 to production intervals 44, 50, respectively. Preferably, fluid flow through cross-over ports 90, 92 is controlled by suitable valves that are opened and closed by conventional means.

Refernug now to figure 9, when the treahnent operation is a frac pack, the objective is to enhance the permeability of the treated formation by delivering a fluid slurry contairng proppants 96 at a high flow rate and in a large volume above the fracture gradient of the connation such that fracturesmaybe formed within the formation 14 end held openbyproppants :5 96. In addition, a free pack also has the objective of preventing the production of fines by packing production interval 44 with proppants 96.

In the initial phase ofthe treatment process ofthe present invention, the interior of sand control screen assemblies 40 is filled with a sand plug 96A. This is achieved by pumping treatment fluid downhole such as a relatively low viscosity oil or water based liquid including so a high concentration of solid agents such as sand, gravel or proppants, that will fall out of the slurry relatively easily to form sand plug 96A. Sand plug 96A improves the ability of one-way valves 70 of sand control screenassembly 40 to prevent fluid flow from the interior to the exterior of sand control screen assembly 40. addition, sand plug 96A prevents sand control screen assembly 40 from seeing the pressure spike that typically occurs at Me end of a fracture operation. Accordingly, it is preferred Mat sand plug 96A extend past the near end of sand control screen assembly 40 as illustrated. It should be noted that this initial phase of the treatment process may not be necessary if sufficient solid agents fall out of the treatment fluids s during the fracture or frac packing operations.

Referring now to figure 10, once sand plug 96A is deposited in sand control screen assembly 40, the second phase of the treatment process may begin. The treatment fluid used dunug the second phase of the treatment process, which is the fracture operation, may be any appropriate fracturing fluid such as oil, water, an oiVwater emulsion, gelled water or gelled oil lo based fracture fluid having a relatively high viscosity to enhance the fracturing process. This treatment fluid may or may not include solid agents such as sand, gravel or proppants but will usually have a lower concentration of solid agents than the treatment fluid ofthe first phase of the treatment process.

In the illustrated embodiment, the treatment fluid ofthe second phase ofthe treatment Is process includes a low concentration of proppants indicated by reference character 96B. The treatment fluid is pumped through service tool 78 and enters the near end of production interval 44 via cross-over ports 90. As the treatment fluid is being continuously pumped at a high flow rate and in a large volume above the fracture gradient of formation 14 and as no returns are being taken, the treatment fluid fractures formation 14 as indicated by reference character 98.

to Referring now to figure 11, prior to the point at which fractures 98 no longer propagate into formation 14, the third phase of the treatment process begins. The treatment fluid used during this phase may be any suitable fluid such as oil, water, an oiVwater emulsion, gelled water or gelled oil based fluid including a suitable solid agent such as gravel, sand orproppants.

In this phase of the treatment process, the solid agents travel into the newly created fractures to Is prop the fractures open and create a path of high permeability back to wellbore 34. In addition, the solid agents fill production interval 44 between sand control screen assembly 40 and casing 36 to form a gravel pack 96C therein which filters particulate matter out of production fluids once production begins. Upon completion of the frac packing of production interval 44, the valves associated with cross-over ports 90 are closed by conventional means.

Referring now to figure 12, following completion of the first frac packing operation, service tool 78 is operably repositioned to frac pack formation 16. As illustrated by the break between service tool 78 and sand control screen assembly 42, the service tool 78 maybe several feet to several hundred feet uphole of sand control screen assembly 42. Once service tool 78 is positioned, a three-phase treatment process similar to that described above may begin.

Referring now to figure 13, the low viscosity treatment fluid with a high concentration of solid agents is pumped into sand control screen assembly 42 to form sand plug 96D. Fracture s treatment fluid is then pumped through service tool 78, as best seen in figure 14. The treatment fluid enters the near end of production interval 50 via cross-over ports 92. In the illustrated embodiment the fracture fluid contains a low concentration of proppants indicated by 96E. As the fracture fluid is being delivered at a high flow rate and in a large volume above the fracture gradient offormation 16 and as no returns are being taken, the fracture fluids fracture formation lo 16 as indicated by fractures 100.

Referring now to figure 15, toward the end of the fracture operation, the composition of the treatment fluid is changed to include a higher concentration of solid agents. These solid agents are used to prop fractures 100 in formation 16 and to form a gravel pack 96P in production interval 5 0 between sand control screen assembly 42 and casing 32. This three-phase treatment process can be repeated for any number of formations by repositioning service tool 78 sequentially uphole relative to each of the formations requiting treatment. Once all of the Connations are treated and prior to beginning production, sand plugs 96A, 96D must be washed out of sand control screen assemblies 40, 42. As seen in figure 16, service tool 78 may be used to wash out the sand control screen assemblies 40, 42 and work string 32.

an To wash out sand control screen assemblies 40, 42, liquid is delivered through service tool 78 to mix with the solid agents forming sand plugs 96A, 96D. The mixture is allowed to reverse out of world shing 32 via the annulus between service tool 78 and work string 32 as indicated by arrows 105. This process of circulating the solid agents to the surface and lowering service tool 78 farmer into work string 32 continues until substantially all the solid agents in as work string 32 have been Ternoved.

As explained above, different compositions of treahnent fluids are used in the above described method during the different phases of the treatment process. Preferably, the first treatment fluid has a higher concentration of solid agents than the second treahnent fluid. The first treatment fluid requires a higher concentration of solid agents as it is intended to place a so sand plug in the sand control screen assemblies. The second treatment fluid does not require such solid agents as it is intended to fracture the formations. Additionally, the first treatment fluid preferably has a lower density and lower viscosity than the second treatment fluid. The lower density and lower viscosity in the first treatment fluid allow the solid agents to fall out of the slurry easily. The higher density and higher viscosity ofthe second treatment fluid allows the second treatment fluid to effectively fracture the formation.

The third treatment fluid preferably has a higher concentration of solid agents than the second treatment fluid. The third treatment fluid props the fractures and gravel packs the s production intervals surrounding the sand control screen assemblies. Therefore, a higher concentration of solid agents is desirable in the third treatment fluid. Additionally, the third treatment fluid may have a lower density and lower viscosity than the second treatment fluid.

The lower density and lower viscosity in the third treatment fluid allow the solid agents to fall out of the slurry more readily.

lo As should be apparent to those skilled in the art, the above described method allows the use of a relatively simple service tool 78 that allows forthetreatmentofmultiple Connations that are relatively close together. This is achieved by using sand control screen assemblies 40, 42 that include one-way valves 70 that prevent the flow of fluids from the interior to Me exterior of sand control screen assemblies 40, 42. Accordingly, fewer tools are required between sand Is control screen assemblies 40, 42, thereby the distance between sand control screen assemblies 40, 42 may be reduced. This reduced distance and the simplicity of service tool 78 allow relatively narrow and relatively closely spaced formations to be treated according to the present invention.

Referring now to figure 17, therein is depicted an embodiment of the present invention to that is used during a gravel packing treatment. As illustrated, sand control screen assembly 40 having one-way valves 70 is positioned within casing 36 and is adjacent to formaffon 14.

Similarly, sand control screen assembly 42 having one-way valve 70 is positioned within casing 36 and is adjacent to formation 16. A wash pipe 104 extends through work string 32 traversing cross-over assembly 106. Cross-over assembly 106 is positioned within work string 32 adjacent to cross-over ports 90 that include valves therein as explained above.

Sand control screen assemblies 40, 42 each have a filter medium associated therewith that is designed to allow fluid to flow therethrough but prevent particulate matter of sufficient size from flowing therethrough. The exact design of the filter medium of sand control screen assemblies 40, 42 is not critical to the present invention as long as it is suitably designed for the so characteristics of the formation fluids and the treatment fluids. One-way valves 70 of sand control screen assemblies 40, 42 may be of any suitable type so long as they prevent fluid flow from the interior to the exterior of sand control screens 40, 42.

To begin the gravel packing completion process, production interval 44 proximate formation 14 and production interval 50 proximate second Connation 16 are isolated. Packer 46 seals the near end of production interval 44 and packer 48 seals the far end of production interval 44. Similarly, paclcer 52 seals the near end of production interval 50 and packer 54 seals the far end of production interval 50. Initially, as illustrated, the cross-over assembly 106 is located proximate to sand control screen assembly 40 and aligned with cross-over ports 90.

Referring to figure 18, when the treatment operation is a gravel pack the objective is to uniformly and completely fill production interval 44 between sand control screen assembly40 and casing 36 with gravel. To help achieve this result, return fluid is taken through sand control lo screen assembly 40, indicated by arrows 108, and travels through wash pipe 104, as indicated by arrows 110, for return to the surface.

More specifically, a treatment fluid, in this case a fluid slurry contanung gravel 112 is pumped downhole in work string 32, as indicated by arrows 114, and into production interval 44 via cross-over assembly 106, as indicated by arrows 116. As the fluid slurry containing is gravel 112 travels to the far end of productioninterval 44, gravel 112 drops out ofthe slurry and builds up from formation 14, filling the perforations and production interval 44 around sand control screen assembly 40 forming gravel pack 112A. While some of the carrier fluid in the slurry may leak off into formation 14, the remainder of the carrier fluid passes through sand control screen assembly40 through one-way valves 70, as indicated by arrows 108. The fluid to flowing back through sand control screen assembly 40, as explained above, follows the paths indicated by arrows 110 back to the surface.

After the gravel packing operation of production interval 44 is complete, cross-over assembly 106 and wash pipe 104 may be moved uphole such that other production intervals may be gravel packed, such as production interval 50, as best seen in figure 19. As the distance Is between formation 14 and formation 16 maybe hundreds or even thousands offeet and as there may be any number of production internals that require gravel pacldug, there may be a considerable amount oftime between the gravel packing of production interval 44 and eventual production Mom formation 14. It has been found thatin conventional completions, considerable fluid loss may occur from the interior of sand control screen assembly 40 through gravel pack so 1 1 2A and into formation 14. This fluid loss is not only costly but may also damage gravel pack 1 1 2A, Connation 14 or both. Using the sand control screen assemblies of the present invention, however, prevents such fluid loss using a seal member, in this case, one-way valves 70, positioned within sand control screen assembly 40. Accordingly, one-way valves 70 not only save the expense associated with fluid loss but also protect gravel pack 112A and formation 14 from the damage caused by fluid loss.

Referring to figure 20, the process of gravel packing production internal 50 is depicted.

Washpipe 104is now disposedwithin sand control screen assembly42. Washpipe 104 extends through cross-over assembly 106 such that return fluid passing through sand control screen assemblies 42, indicated by arrows 118, and travels through wash pipe 104, as indicated by arrows 120, for return to the surface.

The fluid slurry containing gravel 112 is pumped downhole through work stung 32, as indicated by arrows 122, and into production interval 50 via cross-over assembly 106 and cross o over ports 92, as indicated by arrows 124. As the fluid slurry containing gravel 112 travels to the far end of production interval 50, the gravel 112 drops out of the slurry and builds up from Connation 16, filling the perforations and production interval 50 around sand control screen assemblies 42 forming gravel pack 112B. While some of the carrier fluid in the slurry may leak off into formation 16, the remainder of the carrier fluid passes through sand control screen assemblies 42 through ore-way valves 70, as indicated by arrows 118. The fluid flowing back through sand control screen assembly 42, as explained above, follows the paths indicated by arrows 120 back to the surface. Once gravel pack 112B is complete, cross-over assembly 106 may again be repositioned uphole to gravel pack additionalproduction intervals. As explained above, using sand control screen assembly 42 prevents fluid loss from the interior of sand to control screen assembly 42 to formation 16 during such subsequent operations.

As should be apparent to those skilled in the art, even though figures 8 20 present the treatment of multiple intervals of a wellbore in a vertical orientation with packers at the top and bottom of the production interval, these figures are intended to also represent wellbores that have alternate directional orientations such as inclined wellbores and horizontal wellbores. In Is the horizontal orientation, for example, packer 46 is at the heel of production interval 44 and packer 48 is at the toe of production interval 44. Likewise, while multiple production internals have been described as being treated during a single trip, the methods described above are also suitable for treating a single production internal traversed by a wellbore or may be accomplished in multiple trips into a wellbore.

While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodunents as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.

Claims

Claims 1. A single trip method for treating multiple formations traversed

by a wellbore comprising the steps of: respectively positioning sand control screen assemblies within production intervals of the wellbore proximate the formations; preventing fluid flow from the interior to the exterior of the sand control screen assemblies; operably positioning a service tool relative to one of the sand control screen assemblies; pumping a treatment fluid through the service tool into one of the production intervals; and repeating the steps of operably positioning the service tool and pumping a treatment fluid for each of the formations to be treated.
2. A method according to claim 1, wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises operably associating a seal member with each of the sand control screen assemblies.
3. A method according to claim 1, wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises operably associating at least one valve with each of the sand control screen assemblies.
4. A method according to claim 1, wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises operably associating a sleeve with each of the sand control screen assemblies.
5. A method according to claim 1, wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises operably positioning a removable plug within openings of each the sand control screen assemblies.
6. A method according to claim 1, wherein the steps of pumping a treatment fluid further comprise filling the interior of the respective sand control screen assemblies with sand plugs.
7. A method according to claim 1, wherein the steps of pumping a treatment fluid further comprise pumping a fracture fluid and fracturing the respective formations.
8. A method according to claim 1, wherein the steps of pumping a treatment fluid further comprise pumping a gravel packing fluid and gravel packing the respective production intervals.
9. A single trip method according to claim 1, wherein first and second sand control screen assemblies are respectively located within first and second production intervals of a wellbore proximate first and second formations; the service tool is operably positioned relative the first sand control screen assembly; a first treatment fluid containing first solid agents is pumped through the service tool into the interior of the first sand control screen assembly to place a sand plug therein; a second treatment fluid is pumped through the service tool into the first formation to fracture the first formation; a third treatment fluid containing second solid agents is pumped into the first production interval to pack the first production interval with the second solid agents; the pumping of the third treatment fluid is terminated; the service tool is operably positioned relative to the second sand control screen assembly; a fourth treatment fluid containing third solid agents is pumped through the service tool into the interior of the second sand control screen assembly to place a sand plug therein; a fifth treatment fluid is pumped through the service tool into the second formation to fracture the second formation; a sixth treatment fluid containing fourth solid agents is pumped into the second production interval to pack the second production interval with the fourth solid agents; and the pumping of the sixth treatment fluid is terminated.
10. A single trip method according to claim 1, wherein at least two sand control screen assemblies are respectively positioned within production intervals of the wellbore proximate the formations; the pumping of the treatment fluid is terminated; the service tool is operably positioned relative to another one of the sand control screen assemblies; the treatment fluid is pumped through the service tool into another one of the production intervals; and the pumping of the treatment fluid is terminated.
11. A method according to claim 1O, wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises preventing fluid flow from the interior to the exterior of the sand control screen assemblies with a plurality of one-way valves disposed within the sand control screen assemblies.
12. A method according to claim 11, further comprising the step of allowing fluid flow from the exterior to the interior of the sand control screen assemblies through the one-way valves.
13. A method according to claim 12, wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises preventing fluid flow from the interior to the exterior of the sand control screen assemblies with sleeves disposed within the sand control screen assemblies.
14. A method according to claim 13, further comprising the step of allowing fluid flow through the sand control screen assemblies by axially shifting the sleeves from first positions to second positions.
15. A method according to claim 13, further comprising the step of allowing fluid flow through the sand control screen assemblies by rotatably shifting the sleeves from first positions to second positions.
16. A method according to claim 13, further comprising the step of allowing fluid flow through the sand control screen assemblies by removing the sleeves.
17. A method according to claim 10, wherein the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises preventing fluid flow from the interior to the exterior of the sand control screen assemblies with a plurality of plugs disposed within the sand control screen assemblies.
18. A method according to claim 17, further comprising the step of allowing fluid flow between the interior and the exterior of the sand control screen assemblies by mechanically removing the plugs.
19. A method according to claim 17, further comprising the step of allowing fluid flow between the interior and the exterior of the sand control screen assemblies by chemically removing the plugs.
20. A method according to any one of claims 10 to 19, wherein the steps of pumping a treatment fluid further comprise pumping a fracture fluid and fracturing the respective formations.
21. A method according to any one of claims 10 to 19, wherein the steps of pumping a treatment fluid further comprise pumping a gravel packing fluid and gravel packing the respective production intervals.
22. A method according to any one of claims 10 to 21, further comprising the step of continuing to prevent fluid flow from the interior to the exterior of the sand control screen assemblies after the steps of terminating the pumping of the treatment fluid.
23. A single trip method according to claim 1, wherein first and second sand control screen assemblies are respectively located within the wellbore proximate first and second formations; the service tool is operably positioned relative to the first sand control screen assembly; the treatment fluid is a fracture fluid which is pumped into the first formation to fracture the first formation; the pumping of the fracture fluid is terminated; the service tool is operably positioned relative to the second sand control screen assembly; the fracture fluid is pumped into the second formation to fracture the second formation; and the pumping of the fracture fluid is terminated.
24. A method according to claim 23, wherein the step for preventing fluid flow from the interior to the exterior of the sand control screen assemblies further comprises preventing fluid flow from the interior to the exterior of the sand control screen assemblies with a plurality of one-way valves disposed within the sand control screen assemblies.
25. A method according to claim 23 or 24, further comprising the step of continuing to prevent fluid flow from the interior to the exterior of the sand control screen assemblies after the steps of terminating the pumping of the fracture fluid.
26. A single trip method according to claim 1, wherein first and second sand control screen assemblies are respectively positioned within first and second production intervals of a wellbore proximate first and second formations; the service tool is operably positioned relative to the first sand control screen assembly; the interior of the first sand control screen assembly is filled with a sand plug; the first production interval is treated; the service tool is operably positioned relative to the second sand control screen assembly, the interior of the second sand control screen assembly is filled with a sand plug; and the second production interval is treated.
27. A method according to claim 26, wherein steps of treating the first and second production intervals further comprise the steps of pumping a fracture fluid into the first and second formations to fracture the first and second formations.
28. A method according to claim 26 or 27, further comprising the step of preventing fluid flow from the interior to the exterior of the sand control screen assemblies.
29. A method according to claim 26 wherein steps of treating the first and second production intervals further comprise pumping a gravel packing fluid into the first and second production intervals to gravel pack the first and second production intervals.
30. A method according to claim 26, wherein the steps of filling the interior of the sand control screen assemblies with the sand plug further comprise pumping a first treatment fluid containing first solid agents into the interior of the sand control screen assemblies and wherein the steps of treating the production intervals further comprise pumping a second treatment into the formations and pumping a third treatment fluid containing second solid agents into the production intervals.
31. A method according to claim 30, wherein the steps of pumping a second treatment fluid further comprise pumping a second treatment fluid comprising third solid agents.
32. A method according to claim 31, wherein the concentration of the third solid agents in the second treatment fluid is lower than the concentration of first solid agents in the first treatment fluid.
33. A method according to claim 31, wherein the concentration of the third solid agents in the second treatment fluid is lower than the concentration of second solid agents in the third treatment fluid.
34. A method according to claim 30, further comprising the step of preventing fluid flow from the interior to the exterior of the sand control screen assembly with at least one valve operably associated with a base pipe of the sand control screen assembly that controls fluid flow through openings of the base pipe.
35. A method according to claim 30, further comprising the step of preventing fluid flow from the interior to the exterior of the sand control screen assembly with a seal member operably associated with a base pipe of the sand control screen assembly that controls fluid flow through openings of the base pipe.
36. A method according to any one of claims 30 to 35, wherein the viscosity of the second treatment fluid is higher than the viscosity of the first treatment fluid.
37. The method according to any one of claims 30 to 35, wherein the viscosity of the second treatment fluid is higher than the viscosity of the third treatment fluid.
38. A method according to claim 1, wherein, after locating a sand control screen assembly within a production interval of the wellbore and before a production interval is treated, the interior of the sand control screen assembly is filled with a sand plug.
39. A method according to claim 38, wherein the step of treating the production interval further comprises the steps of pumping a fracture fluid into a formation traversed by the wellbore and fracturing the formation.
40. A method according to claim 38, wherein the step of treating the production interval further comprises the step of pumping a gravel packing fluid into the production interval and gravel packing the production interval.
41. A method according to claim 38, wherein the step of filling the interior of the sand control screen assembly with a sand plug further comprises pumping a first treatment fluid containing first solid agents into the interior of the sand control screen assembly and wherein the step of treating the production interval further comprises the steps of pumping a second treatment fluid into a formation traversed by the wellbore, pumping a third treatment fluid containing second solid agents into the production interval, and terminating the pumping of the third treatment fluid when the production interval is packed with the second solid agents.
42. A method according to claim 41, wherein the step of pumping a second treatment fluid further comprises pumping a second treatment fluid comprising third solid agents.
43. A method according to claim 42, wherein the concentration of the third solid agents in the second treatment fluid is lower than the concentration of first solid agents in the first treatment fluid.
44. A method according to claim 42, wherein the concentration of the third solid agents in the second treatment fluid is lower than the concentration of second solid agents in the third treatment fluid.
45. A method according to claim 41, further comprising the step of preventing fluid flow from the interior to the exterior of the sand control screen assembly with at least one valve operably associated with a base pipe of the sand control screen assembly that controls fluid flow through openings of the base pipe.
46. A method according to claim 41, further comprising the step of preventing fluid flow from the interior to the exterior of the sand control screen assembly with a seal member operably associated with a base pine of the sand control screen assembly that controls fluid flow through openings of the base pine.
47. A method according to claim 41, wherein the viscosity of the second treatment fluid is higher than the viscosity of the first treatment fluid.
48. A method according to claim 41, wherein the viscosity of the second treatment fluid is higher than the viscosity of the third treatment fluid.
49. A single trip method for treating multiple formations, the method being substantially as herein described with reference to and as shown in the accompanying drawings.